1. Field of the Invention
The present invention relates to a liquid ejection device provided with an absorbing member for cleaning an ejection surface having an ejection port that ejects liquid by absorbing the liquid adhering to the ejection surface.
2. Description of the Related Art
A printer employing ink-jet system (hereinafter, referred to as an ink-jet printer) ejects ink from an ink ejection head onto a recording sheet to print images and characters. The ink-jet printer has advantages of low running cost, reduction in size of the printer, and ease of printing color images.
The ink-jet printer supplies ink from an ink tank to an ink liquid chamber of an ink ejection head. The ink liquid chamber is provided with a pressure-generating element, such as a heating resistor or a piezoelectric element. Then, pressure is applied to the ink in the ink liquid chamber by the pressure-generating element, and a droplet of ink is ejected from microscopic ejection ports, i.e., nozzles. In the ink-jet printer, the ejected droplet of ink is allowed to land on a recording sheet or the like, to print images and characters.
In the ink-jet printer, ink other than the droplet of ink ejected from the nozzles, namely, a so-called satellite ink and the like may adhere to the ejection surface provided with the nozzles of the ink ejection head facing the recording sheet. In the ink-jet printer, for instance, when printing has not been performed for a long time, the ink adhering near the nozzles because of the previous printing operation may be evaporated and dried to be thickened and solidified, or the ink at tip ends of the nozzles may be evaporated and dried through opening ends of the nozzles on the ejection surface. In the ink-jet printer, if the thickened and solidified ink is adhering near the nozzles, the thickened and solidified ink may block ejection of the droplet of ink. Therefore, the droplet of ink may not be ejected, or an ejection direction of the droplet of ink may be disordered.
To avoid this, for instance, there is a method of removing the thickened and solidified ink adhering to the ejection surface by pressing a hardish, rubber cleaning blade onto the ejection surface of the ink ejection head and making the cleaning blade slide on the ejection surface. For example, Japanese Unexamined Patent Application Publication No. 57-34969 discloses a method of increasing wiping effect by attaching a plurality of cleaning blades to a rotation shaft, rotating the rotation shaft, and wiping an ejection surface with the cleaning blades.
However, according to the method using the cleaning blades, since the thickened and solidified ink and dusts adhering to the ejection surface are removed by pressing the hardish cleaning blades onto the ejection surface and making the ejection surface slide on the ejection surface, the cleaning blades apply large force to the ejection surface; possibly damaging the ejection surface. In addition, this method provides only the effect of wiping the ejection surface. Therefore, it may be difficult to remove the ink thickened and solidified at the tip ends of the nozzles. Further, with this method of wiping the ejection surface with the use of the cleaning blade, even if the plurality of cleaning blades are used, the cleaning blade may damage the ejection surface, and it may be difficult to remove the thickened and solidified ink near the nozzles, and that at the tip ends of the nozzles. Therefore, according to the method using the cleaning blade, it is difficult to remove the thickened and solidified ink completely, and unprinted spots or lines may appear because the ink is not ejected or the ejection direction of the ink is deviated in printing. This may deteriorate image quality.
As a method for improving the above-described method which uses the rubber blade, there is one which employs a porous body for a wiping member, such as a cleaning roller or cleaning blade. For example, Japanese Unexamined Patent Application Publication No. 4-185450 and Japanese Patent No. 2738855 each disclose such method. Japanese Unexamined Patent Application Publication No. 4-185450 discloses a method of using a cleaning roller made from a porous body for cleaning an ejection surface. Japanese Patent No. 2738855 discloses a method of wiping an excess ink adhering to an ejection surface by using a cleaning blade made from a porous body.
The methods disclosed in Japanese Unexamined Patent Application Publication No. 4-185450 and Japanese Patent No. 2738855 each wipe out dusts while absorbing the ink according to capillarity of cells of the porous body by bringing the cleaning roller or blade of the porous body into contact with the ejection surface. With Japanese Unexamined Patent Application Publication No. 4-185450 and Japanese Patent No. 2738855, absorption of the ink and the dusts into the porous body may prevent the ink and the dusts from adhering to the ejection surface again, and from dispersing inside the device, thereby increasing cleaning effect.
However, according to the methods disclosed in Japanese Unexamined Patent Application Publication No. 4-185450 and Japanese Patent No. 2738855, sucking capability of the porous body is not sufficient for the ink thickened and solidified near the nozzles, which may cause nozzle clogging. Therefore, the thickened and solidified ink may not be removed completely, and may results in that the ink is not ejected or the ink is ejected in the deviated direction.